An antenna system is an indispensable component of any wireless communication network. Wireless communications is presently available in many forms, among which the most common one is cellular/mobile communications.
In a cellular wireless network, the geographical region to be serviced by the network is normally divided into smaller areas called cells. Within each cell are mobile stations (MSs) that are used by users to access the network. A cell may be further divided into multiple sectors and in each sector the coverage is provided by a base station (BS). A BS also serves as a focal point to distribute information to and collect information from MSs that are located in the cell by radio signals that are transmitted by the BS antenna.
There are different types of transmissions carried out by BSs. A BS can send specific data to an individual MS within its sector; a BS may also send a set of common data to all the MSs with its sector; a BS may also send data via a common channel to all the MSs within a cell; and a group of BSs may broadcast information via a common channel simultaneously to all MSs within a group of cells. Depending on the type of transmission, a distinctive set of requirements may be required for the BS antenna system in terms of radiation patterns, power settings, etc. In addition, a frequency-reuse scheme may impose constraints on the antenna system. The extent to which an antenna system meets the wide range of requirements and constraints directly impacts on the wireless network performance. Therefore, there is a need to create an antenna system that is reconfigurable, adjustable, and controllable to enable a BS to carry out transmissions from a type of application to the other.